The present invention relates to a camera view finder, and more particularly, to a view finder in which any one of a plurality of finder field frames can be observed selectively.
The light passing through the taking lens of a single reflex camera is incident on the view finder, so that the finder field and taking lens field coincide. In contrast with this, the view finder of a compact camera is separate from the taking lens so that there is parallax between the finder field and taking lens field. As view finders for compact cameras, there are known Keplerian view finders and inverted Galilean view finders.
Keplerian view finders are comprised by an objective positive lens having for forming a real image of a subject in a real image plane with its top and bottom, and right and left reversed, a prism for converting the real image into an erect image, and a positive eyepiece for enlarging the erected image. Along the finder optical path, a finder field frame for indicating the photographing area, e.g., four L-shaped marks, are disposed in the real image plane of the objective lens. With such a Keplerian view finder, the finder field frame can be observed together with the image of a subject formed in the real image plane.
Inverted Galilean view finders are comprised by a negative lens and a positive eyepiece. As types of inverted Galilean view finders, there are known a bright frame type and an Albada type. In the case of the bright frame type, there is provided a bright frame window which has a plurality of transparent finder field frames. Light passing through the bright frame window is introduced into the view finder optical path so that an image of the finder field frame and the image of the subject are superposed. In the case of the Albada type, a finder field frame is formed on the eyepiece and is observed through the eyepiece as an image of the finder field frame reflected from a half mirror formed on a concave surface of an objective lens. The structure of the view finder of the Albada type is simple, and so it is widely used with compact cameras.
There are known compact cameras which can selectively use either a normal photography mode for taking a subject at a standard focal length or a close-up photography mode for taking an enlarged subject at a near distance. With a compact camera of this type, if the position of the finder field frame is such that during normal photography there is little parallax between the taking lens field and the finder field, the parallax for close-up photography becomes great. In order to compensate for the latter parallax, it is necessary to change the finder field.
There are also known cameras which can selectively use either a full-size photography mode or a half-size photography mode. Recently, it has been desired to develop a compact camera which can selectively use either a full-size photography mode or a panoramic photography mode. With such compact cameras, the size of the picture frame formed on the film changes so that it becomes necessary correspondingly to change the finder field. This problem is present also in single reflex cameras.
There is known an Albada-type inverted Galilean view finder of the type wherein both the near distance finder field frame and the far distance finder field frame are disposed along the finder optical path. The use of two finder field frames poses a problem in that it is difficult for the photographer to determine which finder field frame is to be used. There is also known a bright-frame-type inverted Galilean view finder having a parallax correction device wherein two light shield plates formed with two L-shaped frame marks are moved toward or away from each other as the taking lens is moved for focussing, thereby to adjust the position and size of the finder field. This parallax correction device is however complicated in structure because a linkage mechanism between the taking lens and view finder is required.